Individual animal susceptibility and its relationship to induced adaptation or tolerance in sheep to Galega officinalis L.

Oral administration of Galega officinalis L to sheep demonstrated a marked variation in individual animal susceptibility to the toxic effects of the plant. As little as 5 g/kg of dried ground plant induced moderate tracheal frothing in 1 ewe while nearly 5 times that amount failed to elicit any recognizable toxic effects such as frothing, pulmonary edema or hydrothorax in others. Ten g/kg induced severe effects in 3 ewes. Ewes administered levels of plant between 5 and 24 g/kg had toxic effects whose severity was often unrelated to level administered. There was no apparent difference in average severity of clinical signs of toxicity nor pathologic lesions to challenge doses of 24 g/kg of the plant between groups of ewes with an immediate previous history of increasing doses of the plant and others with no history of ingesting the plant. Previously reported apparent induced adaptation or tolerance to G officinalis L in some animals is more likely to have been a result of the extreme variation in individual animals susceptibility.